1. Field of the Invention
The present invention relates generally to an imaging apparatus, and more particularly to a method for generating a reference signal for use in an imaging apparatus.
2. Description of the Related Art
In prior art an imaging apparatus, such as an ink jet printer, forms an image on a print medium, such as paper, by applying ink to the print medium. Such an ink jet printer includes a reciprocating printhead carrier that transports one or more printheads across the print medium along a bi-directional scanning path defining a print zone of the printer. An ink jet printhead cartridge, for example, includes both an ink tank containing ink and an ink jet printhead for selectively ejecting the ink. Each ink jet printhead cartridge is mounted to the printhead carrier.
An encoder system is provided to track the movement of the printhead carrier along a bi-directional scan path. The encoder system provides a carrier encoder signal which may be used, for example, to determine carrier position, velocity, and acceleration. Typically, a print ASIC generates fire pulses in relation to the carrier encoder signal. This allows dots to be placed accurately with respect to the carrier encoder signal, even in the presence of undesired carrier motion such as vibrations. However, in practice, noise and other encoder related errors associated with the carrier encoder signal result in dot placement errors.